Electrodeposition of metals



' Patented Apr. 16, 1929.

UNITED STATES PATENT OFFICE.

nu:oraonnrosrrron or mums.

No Drawing.

In the electro-deposition of metals in the form of tubes or sheets, itis usual practice to provide upon the mandrel or former and as the baseupon which the deposited metal can grow, a covering or coating of amaterial or mixture of materials which, whilst'havin the necessaryproperties for ensuring a goo birth or initiation of deposit, can bereadily detached from the latter when deposition is completed by meltingso as to allow of, the

convenient withdrawal or removal of the deposited tube or sheet from themandrel or former. A usual procedure is to depositlead or a suitable waximpregnated with graphite or other electrical conducting material uponthe mandrel or former and to electrolytically deposit the tubes orsheets upon the lead or graphite-impregnated wax. On the comple tion ofthe electro-deposition of the tube or sheet, each mandrel is placed in afurnace or otherwise suitably heated to melt the depositin surface oflead or impregnated wax, when t e tube or sheet can be withdrawn orremoved from the mandrel or former.

It will be readily understood that the employment of a specialdepositing surface is a source of expense and such surface is a freuentcause of failure in the electro-depos'it1on. Attempts have been made toprovide a metal or alloy from which the mandrel or former can beconstructed which will serve for the direct deposition of the metalwithout the intermediate coating, but as far as I am aware, acommercially successful result has not so far been attained in thisdirection. It will be appreciated that the metal or alloy used mustprovide a surface upon which a good birth of-deposit can be made, mustbe insoluble or practically insoluble in the electrolyte and must nothave such a degree of attachment to the deposited metal that the lattercannot be removed therefrom by a blow or pressure. y research andexperiment, I have found that a mandrel or former made of an alloy ofsteel and chromium and/or iron and chromium, after having its surfacepolished is capable of successful use for the reception of electrolyticdeposits of iron and other metals. The percentage of chromium in thealloy can be varied without seriously affecting the properties requiredof a mandrel or former, and as hereinbefore indicated, but

Application filed June 80, 1925, Serial No. 40,895, and in Great BritainJuly 24, 1924.

I find an alloy containing iron and/or steel with from 12 to 14 per centchromium gives good results.

I have further found that if for a tubular deposit the mandrel has aslight taper, than after depositing the metal thereon, a subsequentannealing and chilling process results iin tire detachment of the metalfrom the man- My invention comprises therefore the im- I provedmandrels, formers or bases for use in the electro-deposition of metalsmade from an alloy of steel and/or iron and chromium, and having apolished surface.

My invention further comprises the employment in the electro-depositionof oylinders or sleeves of metals, of a tapered mandrel or former madefrom an alloy of steel and/ or iron and chromium.

My invention further com rises the improved process of and means orfacilitating the obtaining of metal cylinders or sleeves deposited onmandrels, consisting in depositing the metal on a preferably taperedmandrel made from an alloy of steel and/or iron and chromium, heatingthe metal and mandrel and then quickly cooling or chilling the metal andmandrel whereby separation of the two is effected.

In one convenient application of the invention to the deposition ofmetal cylinders or sleeves, the chromium alloy mandrel is made with asmall taper and is given a polished surface. The metal is then depositedthereon. The mandrel with the metal thereon is then placed in anannealing furnace and after the requisite temperature for annealingpurposes has been reached and maintained for any desired period, themandrel and metal are lowered into a vat with a cooling fluid therein.The effect of the chilling gctilon is to release the metal from the man-My improved mandrels or formers gives a good birth of deposit, allow ofthe ready detachment or removal of the deposited metal tube or sheettherefrom either before or after the annealing process, and arepractically insoluble in the electrolyte.

It will be understood that ,my invention can be applied to formers ofdisc, ribbon or sheet form which are then made of an alloy of steel andfor iron or chromium, the face of which has been polished. Thedepositedtubular polished tapered cathode made of an alloy containing amajor proportion of iron and a, minorproportion of chromlum, heating thecathode. and deposited metal, then quickly chilling the. metal andcathode Whereby separation of the formed tube and cathode occurs.

y 2. A process for the electrolytic formation of iron tubes whichcomprises electrolytically depositing iron on a tubular polished taperedcathode made of an alloy containing a major proportion of iron and aminor proportion of chromium, heatin the cathode and deposited iron,then quick ly cooling the iron and cathode whereby separation of theformed tube and cathode occurs.

8. A process for the electro-deposition of metals which compriseselectrolytically depositing a metal upon a polished cathode made of analloy containing a major proportion of iron and a minor proportion ofchromium, heating the cathode and deposited metal, then quickly chillingthe metal and cathode whereby separation of the deposited metal andcathode occurs.

In testimony whereof I have signed my name to this specification.

-.- moms WILLIAM smmaa nurcums.

